Auxiliary mixing tool for mixing device having a main mixing tool



1963 w. EIRICH ETAL 3,

AUXILIARY MIXING TOOL FOR MIXING DEVICE HAVING A MAIN MIXING TOOL Filed Feb. 15, 1968 35 ..37 3'5 4 F IG I I3 14 12 126 INVENTORS w/L HELM E/RICH GUSTAV E/R/CH FIGZ fitJm? M United States Patent 3,414,239 AUXILIARY MIXING TOOL FOR MIXING DEVICE HAVING A MAIN MIXING TOOL Wilhelm Eirich, Bahnhofstrasse 19, and Gustav Eirich, Walldurnerstrasse 40, both of Hardheim, Nordbaden, Germany Continuation-impart of application Ser. No. 586,898, Oct. 14, 1966. This application Feb. 13, 1968, Ser. No. 705,167 Claims priority, application Germany, Mar. 12, 1964, E 26,602 5 Claims. (Cl. 259-104) ABSTRACT OF THE DISCLOSURE The disclosure is directed to mixing devices of the type including a substantially horizontal mixing pan for containing material to be mixed, a main mixing tool rotated about a substantially vertical main axis, and at least one auxiliary mixing tool rotated about an upright auxiliary axis spaced radially from the main axis toward the periphery of the pan. In accordance with the disclosure, the auxiliary mixing tool comprises an upright shaft rotatable about the auxiliary axis, rod mounting means extending diametrically of the upright shaft at a point thereof substantially below the normal level of the material in the pan, and a pair of substantially rectilinear and elongated cylindrical rods secured to diametrically opposite ends of said rod mounting means, these rods extending substantially parallel to the upright shaft. The rod mounting means and the cylindrical rods are arranged to be completely immersed within the material below the upper level thereof, with the auxiliary tool being rotated at a velocity which is very substantially higher than the angular velocity of the main mixing tool.

Cross reference to related applications This application is a continuation-in-part of application Ser. No. 586,898, filed Oct. 14, 1966, for Device," and now U.S. Patent No. 3,379,419, issued Apr. 23, 1968. Application Ser. No. 586,898 is, in turn, a streamlined continuation application of application Ser. No. 434,486, filed Feb. 23, 1965, for Device, and now abandoned.

Background of the invention Pan mixers or plate mixers, for mixing materials of all kinds, for example, clay, cham'otte, stoneware materials, glass batches, concrete, foundry, molding sand, lime, sandstone materials, ores, fertilizers, tar, asphalt-containing mixtures, paint mixtures, plastics, pharmaceutical products, foods, forage, etc., are known. The known pan mixers comprise, as a general rule, a horizontal pan or bowl mixer which is either maintained stationary or it rotated about a vertical or inclined axis. The mixing apparatus further includes at least one tool system which is arranged to rotate in the pan about an axis extending either concentrically or eccentrically in respect to the center of the pan. This tool system advantageously may comprise a stirring, mixing, kneading, or crushing device, or a combination thereof.

A disadvantage of known pan mixers of this type is that they have a limited throughput capacity, since the pan diameter cannot be increased at random without considerable expenditures in costs and materials and, in addition, the height of the charge of the material in the mixing pan cannot be increased materially without reducing the mixing and preparation effect, respectively.

There are known pan mixers of this type wherein an auxiliary tool is provided to rotate at high circumferential speed about an axis eccentric to the center line of the ICC pan and eccentric to the axis of rotation of a main tool system. Such an auxiliary tool permits a considerable increase of the height of the charge of the mixing material, and thus a considerable increase of the throughput capacity of the pan mixer. Auxiliary tools of this type usually include several rods extending parallel to the axis of rotation of the tool and arranged around a circular path, with the auxiliary tools being usually driven at variable or reversible circumferential speeds. Such speeds, for example, may be a multiple of the circumferential speed of the main mixing tool system, for example, from two to thirty times the circumferential speed of the main tool system and preferably from three to twenty times such speed.

With an auxiliary tool provided and operated in this manner, it is possible to obtain faster and more thorough mixing of the material, and the throughput capacity can be doubled, with the same processing quality, compared to that of a pan mixer without such an auxiliary tool. This is due to the fact that a substantially greater amount of energy is imparted into the mixing material. However, a disadvantage in arrangements embodying known types of auxiliary mixing tools is that they have great centrifugal effect on the mixing material in the mixing pan, due to their relatively high circumferential speed. Thus, the mixing material is whirled high, and this is particularly dis advantageous when the material is of such a nature as to have a tendency to dust formation. Such high centrifugal speeds are characteristic, for example, of an auxiliary tool where the individual rods are arranged on a radius of 250 mm. from the axis of rotation of the auxiliary tool. and the auxiliary tool is driven at angular velocities of the order of 200 rpm.

By way of example, a known pan mixer comprising a main tool system and such an auxiliary tool is shown and described in Wiegel U.S. Patent No. 3,109,632, issued Nov. 5, 1963, for Mixers. For example, the Wiegel U.S. patent shows, particularly in FIGS. 1a and 2, auxiliary tools 25 which are rotated at an angular velocity which is much higher than the angular velocity than that of the main tool systems supported on the shafts 12.

Summary of the invention This invention relates to pan mixers of the type including one or more main tool systems rotating about axes which are centric or eccentric with respect to a mixing pan and one or more auxiliary tools rotated about axes eccentric to the axes of the main tool systems and rotated at a circumferential speed which is a multiple of the circumferential speed of the main tool system or systems. More particularly, the present invention is directed to a novel and improved auxiliary tool arrangement for this type of mixer.

In accordance with the invention, the auxiliary tool includes a support shaft extending from above the level of material in the mixing pan to a point well beneath the upper level of the material in the mixing pan. A preferably cylindrical cross member is secured to the lower end of this shaft to extend diametrically thereof, and cylindrical rods are secured to opposite ends of the cross member and extend parallel to the axis of rotation of the shaft. The lengths of these cylindrical rods are so selected that they are always immersed beneath the upper surface of the material in the mixing pan.

The support shaft of the auxiliary tool is rotated at an angular velocity which is a multiple of the angular velocity of the main tool system, and this may be accomplished, for example, by driving the support shaft of the auxiliary tool directly by an electric motor which drives the main tool system through reduction gearing. Other driving arrangements may be provided, such as independent drives for the auxiliary tool or tools and for the main tool system or tool systems. It has been found in practice that, using an auxiliary tool of this type and in spite of the high peripheral or circumferential velocity thereof, no material will be hurled out of the mixing pan. Instead, the material is drawn inwardly by the auxiliary tool in the manner of an eddy or vortex. From this, it follows that the drive shaft of the auxiliary tool, in spite of the high angular velocity, is not subjected to significant wear.

Very high peripheral speeds may be used, as the material to be mixed does not spurt upwardly because the H-shaped auxiliary tool is deeply submerged in the material. As stated, the material is very advantageously retracted from the surface in the form of an eddy or vortex. It will be appreciated that the mixing rods, which have a very high circumferential velocity are disposed completely beneath the surface of the material in the mixing pan, and only the drive shaft extends through and above the surface of the material. The drive shaft, due to its very much smaller diameter as compared to the effective diameter of the auxiliary tool beneath the surface of the material, has a relatively small circumferential speed, thereby greatly reducing the wear on the drive shaft.

With the mixing rods rotating at high circumferential speed completely beneath the surface of the material, it is possible to introduce greater energy into the mixing material and to enhance the cutting, grinding, dividing and elimination of lumps in the mixing material. This insures circulation of the mixing material even in the case of hardto-handle moist materials, which are neither completely wet nor completely dry. The wear of the rods of the auxiliary tool can be controlled easily because, when the auxiliary tool moves in counter flow to the direction of rotation of the mixing pan, the material moves away from the pan wall toward the pan center. Thus, little or no mixing material moves between the auxiliary tool and the pan wall. The distance of the bottom or lower ends of the rods of the auxiliary tool from the bottom of the pan can be so selected that a layer of the mixing material serves as a protective layer remaining below these bottom ends while still participating in the circulation although at a somewhat lower speed. This prevents excessive wear of the pan bottom and of the bottom ends of the auxiliary tool. The service life of the auxiliary tool can be increased by armoring the portions thereof beneath the surface of the material with suitable hard materials such as, for example, tungsten carbide.

The auxiliary tool of the invention is preferably so designed that the individual mixing rods are integral with the horizontal cross member which extends radially and diametrically of the support shaft, and the support shaft is made integral with the cross member. The upper end of the support shaft may be provided with a flange coupling or the like whereby it may be secured to a similar flange coupling on a drive shaft. This permits ready interchange of the mixing tool when such may become necessary due to wear, for example.

An object of the present invention is to provide an improved auxiliary tool for pan mixers including one or more main tool systems rotating about axes which are centric or eccentric with respect to a rotating mixing pan.

Another object of this invention is to provide such a mixing tool in which the mixing elements are disposed completely beneath the surface of the material in the mixing pan.

A further object of the invention is to provide such a mixing tool in which, despite the high circumferential or peripheral velocity thereof, no mate-rial is hurled out of the pan and the material is drawn inwardly and downwardly in an eddy or vortex effect.

Still another object of the invention is to provide such a mixing tool including a preferably cylindrical and vertically extending support shaft, at least one preferably cylindrical and diametrically extending cross member secured at its midpoint to the lower end of the support shaft, and a pair of cylindrical rods each secured to a respective end of each cross member and extending parallel to the axis of rotation of the tool, these rods being at all times submerged completely beneath the surface of material in the mixing pan.

A further object of the invention is to provide such an auxiliary tool which is of simple and economical construction and which can readily be replaced when necessary or desirable.

Brief description of the drawings For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a transverse sectional view through a pan mixer embodying the auxiliary tool of the invention; and

FIG. 2 is a plan view of the mixer shown in FIG. 1.

Description of the preferred embodiment Referring to the drawings, a pan mixer is illustrated as including a mixing pan 10 having a cylindrical side wall 11 and a circular bottom wall 12, the bottom wall being formed with a circular discharge aperture 13, all in a known manner. Pan 10 contains the material 14 to be mixed or otherwise processed by the mixing tools, and the upper level of the material 14 in pan 10 is indicated at 15.

A main mixing tool system is generally indicated at 20 as includin an upwardly extending drive shaft 21 which is eccentric relative to pan 10. A socket 22 is keyed or otherwise secured to the lower end of shaft 12 and mounts two or more radial arms 23, four arms 23 being illustrated solely by way of example. Clamps 24 at the ends of arms 23 secure the upper ends of rods 25 each of which extends downwardly into material 14 substantially parallel to the drive shaft 21. The lower end of each 25 has secured thereto, or is integral with, a respective mixing blade 26 positioned slightly above the bottom wall 12 of pan 10.

Each rod 23 has telescoped thereover, intermediate its ends, a respective sleeve 27 which may be clamped and in an adjusted radial position along the respective arm 23. Sleeves 27 have rods 28 extending downwardly therefrom, and each rod 28 carries a respective mixing blade 29 which is disposed below the upper level 15 of material 14 but somewhat above the mixing blade.

While only one tool system 20 is shown in the drawings, it should be understood that two or more main mixing tool systems may be provided for each pan 10. The respective main tool systems may be independently driven, or all of the main tool systems may be driven by a common motor through the medium of suitable transmission means. The operation of the device as thus far described is well known to those skilled in the art, and detailed description is believed unnecessary. Needless to say, as the shaft 21 is rotated, the mixing blades 26 and 29, as well as the rods or arms 25 and 28 thoroughly mix the material, and the mixed material is gradually moved to the discharge opening 13 in the bottom wall 12 of pan 10. Discharge opening 13 is closed by a suitable plate during the actual mixing operation, and is opened only at the end of a mixing operation, for discharge of the mixed material.

As stated, the mixing arrangement shown in the drawings is of the type including an auxiliary stirrer or mixer whose circumferential velocity is a multiple of the circumferential velocity of the main mixing or stirring tool system or systems. An auxiliary stirring tool embodying the principles of the invention is illustrated generally at 30. This auxiliary stirrer or stirring tool includes a drive shaft 31 rotatable about an axis eccentric to the axis of rotation of shaft 21 of the main tool system 20. Shaft 31 extends from above the upper level 15 of material 14 to a substantial depth within material 14. For ready replacement of auxiliary stirring tool 30, the upper end of shaft 31, outside material 14 and above level 15 thereof, is provided with a coupling flange 32 which may be disengageably secured to a coupling flange 33 on the lower end of a drive shaft 34 rotatably mounted in suitable bearing means as schematically indicated at 36. Shaft 34 is rotated at an angular velocity such that the circumferential speed, or peripheral speed, of auxiliary stirring tool is a multiple of the circumferential or peripheral speed of the main mixing or stirring tool system 20.

In accordance with the invention, a cross member 37 is secured to the lower end of shaft 31 well beneath the upper level 15 of material 14, cross member 37 being secured to shaft 31 at substantially the mid-point of the cross member. At each end of cross member 37 there is secured a respective mixing rod extending substantially parallel to shaft 31. Rods 35 may have any desired cross section, generally in accordance with the type of mixing to be performed, and the cross sections may be circular, rectangular, square, polygonal, or any other desired configuration. The lengths of rods 35 are so selected, with relation to the extent to which shaft 31 extends beneath the surface 15 of material 14, that rods 35 are always completely submerged within material'14 beneath the upper surface 15 thereof, as will be readily apparent from the drawings. Also, the lower ends of rods 35 are spaced somewhat above the bottom wall of pan 10 to provide a protective layer of materal between this wall and the lower ends of rods 35.

While in FIGS. 1 and 2, only a single cross member 37 is illustrated, it will be readily appreciated that this is exemplary only and that two or more cross rods or cross members 37 may be provided, each having rods 35 secured to its opposite ends. Furthermore, the driving means for the main tool system and for the auxiliary tool 30 have not been illustrated, as these are well known, with a suitable driving means being illustrated, by way of example, in the above-mentioned Wiegel US. Patent No. 3,109,632.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departin from such principles.

What is claimed is:

1. In a mixing device of the type including a substantially horizontal mixing pan, having a bottom wall, for containing material to be mixed, a main mixing tool system rotated about a substantially vertical main axis at a selected circumferential speed, and at least one auxiliary tool rotated about an upright auxiliary axis eccentric with said main axis at a circumferential speed which is a multiple of the circumferential speed of the main mixing tool system; the improvement in which said auxiliary tool comprises, in combination, upright shaft means rotatable about said auxiliary axis and extending a substantial distance beneath the upper surface of the material in said pan; at least one rod mounting means extending diametrically of said upright shaft means at a point thereof substantially below the normal level of the material in said pan; and a pair of substantially rectilinear and elongated rods secured to each rod mounting means on diametrically opposite sides of, and radially spaced from, said up right shaft means, said rods extending substantially parallel to said upright shaft means; said rods being completely submerged within the material in said pan, with their upper ends disposed a substantial distance beneath the upper level of said material and their lower ends disposed above the bottom wall of said pan a distance suflicient to provide a protective layer of material interposed between the lower ends of said rods and the bottom wall of said pan.

2. In a mixing device, the improvement claimed in claim 1, in which said rods have a substantially cylindrical cross section.

3. In a mixing device, the improvement claimed in claim 1, in which said rods extend both upwardly and downwardly from the associated rod mounting means.

4. In a mixing device, the improvement claimed in claim 3, in which each rod mounting means is secured to the lower end of said upright shaft means.

5. In a mixing device, the improvement claimed in claim 1, in which said upright shaft means includes a support shaft having said rod mounting means secured thereto and having its upper end projecting above the normal level of material in said pan; a first disengageable coupling means on the upper end of said support shaft; a drive shaft substantially coaxial with said support shaft; and a second disengageable coupling element on the lower end of said drive shaft and disengageable connectable to said first disengageable coupling; whereby said auxiliary tool may be readily uncoupled from said drive shaft for replacement when necessary or desirable.

References Cited UNITED STATES PATENTS 877,087 1/1908 Kennedy 259-1()8 3,109,632 11/1963 Wiegel 259-84 3,189,326 6/1965 Brown 259-84 X 3,215,412 11/1965 Kindl r 259179 ROBERT W. JENKINS, Primary Examiner. 

